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restructure onChannelMessage

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This commit is contained in:
ansuz 2019-08-22 11:21:10 +02:00
parent 8af7308da4
commit 338f967149
1 changed files with 84 additions and 34 deletions
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118
historyKeeper.js
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@ -220,6 +220,10 @@ module.exports.create = function (cfg) {
if the channel exists but its index does not then it caches the index
*/
const getIndex = (ctx, channelName, cb) => {
// FIXME don't allow more than one index to be computed at a time
// if one is in progress, the callback to a queue
// whenever you completed, empty the queue in order
const chan = ctx.channels[channelName];
if (chan && chan.index) {
// enforce async behaviour
@ -262,6 +266,8 @@ module.exports.create = function (cfg) {
TODO rename maybeMsgHash to optionalMsgHash
*/
const storeMessage = function (ctx, channel, msg, isCp, maybeMsgHash) {
// TODO implement a queue so that we know messages are written in order
const msgBin = new Buffer(msg + '\n', 'utf8');
// Store the message first, and update the index only once it's stored.
// store.messageBin can be async so updating the index first may
@ -312,55 +318,96 @@ module.exports.create = function (cfg) {
* caches the id of the last saved checkpoint
* adds timestamps to incoming messages
* writes messages to the store
*/
const onChannelMessage = function (ctx, channel, msgStruct) {
// don't store messages if the channel id indicates that it's an ephemeral message
if (!channel.id || channel.id.length === EPHEMERAL_CHANNEL_LENGTH) { return; }
const isCp = /^cp\|/.test(msgStruct[4]);
if (metadata_cache[channel.id] && metadata_cache[channel.id].expire &&
metadata_cache[channel.id].expire < +new Date()) {
return; // Don't store messages on expired channel
// TODO if a channel expired a long time ago but it's still here, remove it
}
let id;
if (isCp) {
/*::if (typeof(msgStruct[4]) !== 'string') { throw new Error(); }*/
// id becomes either null or an array or results...
id = CHECKPOINT_PATTERN.exec(msgStruct[4]);
if (Array.isArray(id) && id[2] && id[2] === channel.lastSavedCp) {
// Reject duplicate checkpoints
return;
}
}
var metadata = metadata_cache[channel.id];
if (metadata && metadata.validateKey) {
/*::if (typeof(msgStruct[4]) !== 'string') { throw new Error(); }*/
let signedMsg = (isCp) ? msgStruct[4].replace(CHECKPOINT_PATTERN, '') : msgStruct[4];
signedMsg = Nacl.util.decodeBase64(signedMsg);
// FIXME PERFORMANCE: cache the decoded key instead of decoding it every time
// CPU/Memory tradeoff
const validateKey = Nacl.util.decodeBase64(metadata.validateKey);
const validated = Nacl.sign.open(signedMsg, validateKey);
if (!validated) {
Log.info("HK_SIGNED_MESSAGE_REJECTED", 'Channel '+channel.id);
return;
let metadata;
nThen(function (w) {
// getIndex (and therefore the latest metadata)
getIndex(ctx, channel.id, w(function (err, index) {
if (err) {
w.abort();
return void Log.error('CHANNEL_MESSAGE_ERROR', err);
}
if (!index.metadata) {
// if there's no channel metadata then it can't be an expiring channel
// nor can we possibly validate it
return;
}
metadata = index.metadata;
if (metadata.expire && metadata.expire < +new Date()) {
// don't store message sent to expired channels
w.abort();
return;
// TODO if a channel expired a long time ago but it's still here, remove it
}
// if there's no validateKey present skip to the next block
if (!metadata.validateKey) { return; }
// trim the checkpoint indicator off the message if it's present
let signedMsg = (isCp) ? msgStruct[4].replace(CHECKPOINT_PATTERN, '') : msgStruct[4];
// convert the message from a base64 string into a Uint8Array
// FIXME this can fail and the client won't notice
signedMsg = Nacl.util.decodeBase64(signedMsg);
// FIXME this can blow up
// TODO check that that won't cause any problems other than not being able to append...
const validateKey = Nacl.util.decodeBase64(metadata.validateKey);
// validate the message
const validated = Nacl.sign.open(signedMsg, validateKey);
if (!validated) {
// don't go any further if the message fails validation
w.abort();
Log.info("HK_SIGNED_MESSAGE_REJECTED", 'Channel '+channel.id);
return;
}
}));
}).nThen(function () {
// do checkpoint stuff...
// 1. get the checkpoint id
// 2. reject duplicate checkpoints
if (isCp) {
// if the message is a checkpoint we will have already validated
// that it isn't a duplicate. remember its id so that we can
// repeat this process for the next incoming checkpoint
// WARNING: the fact that we only check the most recent checkpoints
// is a potential source of bugs if one editor has high latency and
// pushes a duplicate of an earlier checkpoint than the latest which
// has been pushed by editors with low latency
// FIXME
if (Array.isArray(id) && id[2]) {
// Store new checkpoint hash
channel.lastSavedCp = id[2];
}
}
}
if (isCp) {
// WARNING: the fact that we only check the most recent checkpoints
// is a potential source of bugs if one editor has high latency and
// pushes a duplicate of an earlier checkpoint than the latest which
// has been pushed by editors with low latency
// FIXME
if (Array.isArray(id) && id[2]) {
// Store new checkpoint hash
channel.lastSavedCp = id[2];
}
}
msgStruct.push(now());
storeMessage(ctx, channel, JSON.stringify(msgStruct), isCp, getHash(msgStruct[4]));
// add the time to the message
msgStruct.push(now());
// storeMessage
storeMessage(ctx, channel, JSON.stringify(msgStruct), isCp, getHash(msgStruct[4]));
});
};
/* dropChannel
@ -673,6 +720,9 @@ module.exports.create = function (cfg) {
}
metadata.channel = channelName;
// XXX check that the validateKey is valid, otherwise send an error?
// don't bother putting it into storage
nThen(function (waitFor) {
var w = waitFor();